Liquid crystal display device including pixel electrodes with slits and protrusion between common electrode and alignment film

ABSTRACT

In a vertical aligned LCD the other substrate has further protrusion parts e.g. parallel to the gate buses or source buses, in addition to the protrusion parts parallel to slits of pixel electrodes. By the further protrusion, when a voltage is applied to the liquid crystal layer, it becomes easy to align axes of liquid crystal molecules in one direction, so that transmittivity of light which travels through liquid crystal panel becomes high.

DETAILED DESCRIPTION OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display devicecomprising a first substrate having a pixel electrode and a firstalignment film, and a second substrate having a common electrode and asecond alignment film.

2. Prior Art

Recently, as liquid crystal display devices in which a lighttransmissivity and a viewing angle can effectively be improved, liquidcrystal display devices adopting a multiple domain vertical alignment(or SVA; Super Vertical Alignment) method have come into wide use. As anexample of such conventional liquid crystal display devices in which theSVA method has been adopted, a liquid crystal display device having aTFT substrate with a TFT (thin film transistor) formed thereon and acolor filter substrate with a color filter formed thereon willhereinafter be described.

FIGS. 6 through 9 are schematic explanatory views of a conventionalliquid crystal display device adopting the SVA method.

FIG. 6 includes an enlarged plan view (A) of a portion of the TFTsubstrate in this conventional liquid crystal display device whichcorresponds to one pixel, and a cross-sectional view (B) of the portiontaken along line A—A. FIG. 6(A) shows only a gate bus, source buses anda pixel electrode, and a TFT is omitted from the drawing.

As shown in FIG. 6(A), this TFT substrate 10 is formed with a gate bus11 and source buses 12. Further, the TFT substrate 10 is formed with apixel electrode 13 and a TFT (not shown) correspondingly to each pixel.Slits 13 b (portions indicated by multiple dots) are formed at thecentral part of the pixel electrode 13. Further, slits 13 a and slits 13c (portions indicated by multiple dots) are formed at the upper andlower portions (in the drawing) of the pixel electrode 13, respectively.Gaps 14 are provided between the source buses 12 and the pixel electrode13.

As shown in FIG. 6(B), the surface of the TFT substrate 10 is coveredwith an alignment film 15. This alignment film 15 is omitted in FIG.6(A). The TFT substrate 10 is opposed to a color filter substrate via aliquid crystal layer.

FIG. 7 includes a plan view (A) of the TFT substrate and the colorfilter substrate opposed to each other via the liquid crystal layer asviewed from the color filter substrate side, and a cross-sectional view(B) of these two substrates taken along line B—B. To illustratecharacteristic portions of this conventional liquid crystal displaydevice in a simplified manner, FIG. 7(A) shows only the gate bus, thesource buses, the pixel electrode and protrusions (or ridges).

As shown in FIG. 7(B), the TFT substrate 10 is opposed to the colorfilter substrate 20 via the liquid crystal layer 30. This liquid crystallayer 30 is constituted of negative liquid crystal molecules havingproperties to be aligned perpendicularly to electric force lines.

The color filter substrate 20 is provided with a color filter (notshown). Further, the color filter substrate 20 is provided with a commonelectrode 21 on which protrusions (or ridges) 22 are formed. As shown inFIG. 7(A), these projections 22 are formed on the right-hand andleft-hand sides of the slits 13 b in parallel thereto. A material forthese protrusions 22 may be selected, for example, from phenolic resins,novolac resins, and acrylic resins. Further, as shown in FIG. 7(B), thecommon electrode 21 and the protrusions 22 are covered by an alignmentfilm 23. In this way, protrusions 22 are formed between the commonelectrode 21 and the alignment film 23, so that the surface of the colorfilter substrate 20 is formed with portions 24 which are projectedtoward the liquid crystal layer 30 caused by the protrusions 22. Sincethe protrusions 22 are formed in parallel to the slits 13 b as shown inFIG. 7(A), the projected portions 24 are formed also in parallel to theslits 13 b.

The alignment films 15 and 23 formed on the TFT substrate 10 and thecolor filter substrate 20, respectively, are adapted to align liquidcrystal molecules perpendicularly to these alignment films 15 and 23,when no voltage is applied to the liquid crystal layer 30.

Description will now be made on the behavior of the liquid crystalmolecules when a voltage is applied between the substrates 10 and 20with reference to FIG. 8 and FIG. 9 showing the liquid crystal moleculesmore distinctly.

FIG. 8 is a cross-sectional view of the device taken along line C—C whenno voltage is applied between the substrates 10 and 20 in FIG. 7, andFIG. 9 is the same cross-sectional view when a voltage is appliedbetween the substrates 10 and 20 in FIG. 7. The liquid crystal moleculesare indicated by ellipses.

As shown in FIG. 8, when no voltage is applied (hereinafter referred toas “voltage non-applied period”), the liquid crystal molecules in theliquid crystal layer 30 are oriented perpendicularly to the alignmentfilm 23 (i.e., to each of the substrates 10 and 20). In the state thatthe liquid crystal molecules are perpendicularly oriented, when avoltage is applied, electric force lines as represented by broken linesdevelop. As the liquid crystal molecules constituting the liquid crystallayer 30 are negative liquid crystal molecules, they start to beinclined perpendicularly to the electric force lines (horizontally withrespect to the substrates 10 and 20). In this case, the electric forcelines develop substantially perpendicularly to the substrates 10 and 20.However, as the slits 13 b (See FIG. 6) are provided in the pixelelectrode 13, and the gap 14 (See FIG. 6) is provided between the pixelelectrode 13 and the source bus 12, the electric force lines around theslit 13 b and the gap 14 are slightly bent and enter/leave the pixelelectrode 13. Accordingly, immediately after the development of theseelectric force lines, the electric force lines enter/leave those liquidcrystal molecules present in positions away from the slit 13 b and thegap 14 substantially in parallel thereto, but enter/leave at a slightlyinclined angle those liquid crystal molecules present in positionsaround the slit 13 b and the gap 14 under the influence of the slit 13 band the gap 14. Therefore, the liquid crystal molecules 31 and 32present around the slit 13 b and the gap 14 start to be inclinedhorizontally to the substrates 10 and 20 earlier than the liquid crystalmolecules present in the positions away from the slit 13 b and the gap14. When the liquid crystal molecules 31 and 32 start to be inclined,the other liquid crystal molecules sequentially start to be inclinedfrom the liquid crystal molecules 31 and 32 as their starting points. Inthis case, when considering the directions of the electric force linesthat enter/leave the respective liquid crystal molecules 31 and 32, theliquid crystal molecule 31 starts to be oriented perpendicularly to theelectric force line while being inclined in the clockwise direction T,whereas the liquid crystal molecule 32 starts to be orientedperpendicularly to the electric force line while being inclined in thecounterclockwise direction T′. Accordingly, the liquid crystal moleculespositioned in a region A closer to the slit 13 b than the gap 14 aregreatly influenced by the liquid crystal molecule 31 inclined in theclockwise direction T, and sequentially become inclined in the clockwisedirection T. On the other hand, the liquid crystal molecules existing ina region B closer to the gap 14 are greatly influenced by the liquidcrystal molecule 32 inclined in the counterclockwise direction T′, andsequentially become inclined in the counterclockwise direction T′. As aresult, during the voltage-applied period, the directions of inclinationof the liquid crystal molecules in the regions A and B are opposite toeach other, and the liquid crystal molecules are oriented as shown inFIG. 9.

PROBLEMS THAT THE INVENTION IS TO SOLVE

As shown in FIG. 9, when the liquid crystal molecules are inclined inopposite directions in the regions A and B, the boundary between theregions A and B becomes a disclination line, which reduces the lighttransmittance.

It is therefore an object of the present invention to provide a liquidcrystal display device which has an improved light transmissivity of aliquid crystal layer when a voltage is applied.

MEANS FOR SOLVING THE PROBLEMS

To achieve the above object, the liquid crystal display device of thepresent invention comprises a first substrate having a pixel electrodeand a first alignment film, and a second substrate having a commonelectrode and a second alignment film, the first substrate and thesecond substrate sandwiching a liquid crystal layer therebetween, and ischaracterized in that

said pixel electrode has at least one first slit, or said firstsubstrate has at least one first protrusion between the pixel electrodeand the first alignment film,

and in that the common electrode has a second slit extending in adirection different from a direction in which the first slit or thefirst protrusion extends, or the second substrate has a secondprotrusion between the common electrode and the second alignment film,the second slit or the second protrusion extending in a directiondifferent from the direction in which the first slit or the firstprotrusion extends.

In the liquid crystal display device of the present invention, thecommon electrode has the second slit extending in a direction differentfrom the direction in which the first slit or the first protrusionextends, or the second substrate has the second protrusion between thecommon electrode and the second alignment film, the second protrusionextending in a direction different from the direction in which the firstslit or the first protrusion extends. In this way, the second slit orthe second protrusion of the second substrate extends in a directiondifferent from the direction in which the first slit or the firstprotrusion of the first substrate extends, as a result of which itbecomes possible to align the liquid crystal molecules in a desireddirection when a voltage is applied to the liquid crystal layer (themanner in which the alignment of liquid crystal molecules is controlledwill be described later in detail with reference to some embodiments ofthe invention). Thus, it becomes possible to control the alignment ofthe liquid crystal molecules such that the transmissivity of lightthrough the liquid crystal layer is improved when a voltage is appliedto the liquid crystal layer.

In the liquid crystal display device of the present invention, it ispreferable that the first substrate has a gate bus and a source bus, andthat the second slit or the second protrusion (or the first slit or thefirst protrusion) is parallel to at least one of the gate bus and sourcebus.

By forming the second slit or the second protrusion in parallel to atleast one of the gate bus or the source bus, it becomes possible tocontrol the alignment of the liquid crystal molecules such that thetransmissivity of light through the liquid crystal layer is improvedwhen a voltage is applied to the liquid crystal layer.

In the liquid crystal display device of the present invention, it ispreferable that the second slit or the second protrusion is formed at aposition which opposes a central portion of the pixel electrode.

By forming the second slit or the second protrusion at the positionopposing the central portion of the pixel electrode, it also becomespossible to control the alignment of the liquid crystal molecules suchthat the transmissivity of light through the liquid crystal layer isimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a TFT substrate and a color filter substrate opposed toeach other via a liquid crystal layer, wherein 1(A) is a plan view ofthe substrates viewed from the color filter substrate side, and 1(B) isa cross-sectional view of these two substrates taken along line B—B;

FIG. 2 is an illustration showing the alignment of the liquid crystalmolecules during the voltage non-applied period at a cross-section takenalong line C—C of FIG. 1;

FIG. 3 is an illustration showing the alignment of the liquid crystalmolecules during the voltage-applied period at the cross-section takenalong line C—C of FIG. 1;

FIG. 4 is a plan view of the device in which only the protrusions 25parallel to the source buses 12 are provided;

FIG. 5 is a view schematically showing a cross section of a liquidcrystal display device having a common electrode provided with slits;

FIG. 6 shows a conventional liquid crystal display device, wherein 6(A)is an enlarged plan view of a portion thereof corresponding to one pixelof a TFT substrate provided in the device and 6(B) is a cross-sectionalview of the portion taken along line A—A;

FIG. 7 shows the TFT substrate and the color filter substrate opposed toeach other via a liquid crystal layer, wherein 7(A) is a plan view ofthe substrates as viewed from the color filter substrate side, and 7(B)is a cross-sectional view of these two substrates taken along line B—B;

FIG. 8 is a cross-sectional view of the device taken along line C—C ofFIG. 7 when no voltage is applied between the substrates 10 and 20; and

FIG. 9 is a cross-sectional view of the device taken along line C—C ofFIG. 7 when a voltage is applied between the substrates 10 and 20.

EMBODIMENTS OF THE INVENTION

Embodiments of the present invention will be described hereinafter.

FIGS. 1 and 2 are schematic explanatory views of a liquid crystaldisplay device according to a first embodiment of the present invention.

FIG. 1 includes a plan view (A) of a TFT substrate and a color filtersubstrate opposed to each other via a liquid crystal layer viewed fromthe color filter substrate side, and a cross-sectional view (B) of thesetwo substrates taken along line B—B. In the following description of theliquid crystal panel of FIG. 1, those components identical with those ofthe liquid crystal panel shown in FIG. 7 are indicated by the samereference numerals, respectively, and only those points different fromthe liquid crystal panel shown in FIG. 7 will be described.

The difference between FIG. 1 and FIG. 7 is that in FIG. 1, protrusions25, 26 and 27 are formed, in addition to the protrusion 22 parallel tothe slits 13 b, on the common electrode 21 of the color filter substrate200, so that projected portions 241 are formed on the surface of thecolor filter substrate 200 depending on these protrusions 22, 25, 26 and27. As in the case of the protrusion 22, phenol resin, novolac resin,acrylic resin or the like can be used as the material of the protrusions25, 26 and 27. The present invention does not concern the materialitself of these protrusions. Each protrusion 25 is formed in parallel toa respective one of the source buses 12 over the entire length thereof.As shown in FIG. 1(A), a side edge portion 25 a of the protrusion 25extents to such an extent that it overlaps with an edge portion 13 d ofthe pixel electrode 13. As shown in FIG. 1(A), each protrusion 26 isformed in parallel to the gate bus 11 over a part of the gate bus 11.Further, the protrusion 27 is formed perpendicularly to the source bus12 at a position opposite to a central portion of the pixel electrode13. In the present embodiment, in addition to these protrusions 25, 26and 27, the protrusions 22 parallel to the slits 13 b are also providedas in the case of FIG. 7. These protrusions 22, 25, 26 and 27 aremutually connected into a unitary form. In FIG. 1(A), the portionsthereof corresponding to the protrusions 22 formed in parallel to theslit 13 b are shown by hatching. Further, an alignment film 231 (SeeFIG. 1(B)) is formed on the entire surface of the color filter substrate200 so as to cover the common electrode 21 and the respectiveprotrusions 22, 25, 26 and 27. Since the protrusions 22, 25, 26 and 27are sandwiched between the common electrode 21 and the alignment film231, portions 241 projecting toward the liquid crystal layer 30, causedby the respective protrusions 22, 25, 26 and 27, are formed on thesurface of the color filter substrate 200, as shown in FIG. 1(B). Notethat FIG. 1(B) only shows the projected portions 241 caused by theprotrusions 25 and 27 of the protrusions 22, 25, 26 and 27.

The liquid crystal display device of this embodiment can eliminate thedisclination, by virtue of the effect of the projected portions 241. Themanner in which the disclination is eliminated will be describedhereinafter.

FIG. 2 is a view showing the alignment of the liquid crystal moleculesduring the voltage non-applied period, at a cross-section taken alongline C—C in FIG. 1. FIG. 3 is a view showing the alignment of the liquidcrystal molecules during the voltage-applied period, at the samecross-section.

As shown in FIG. 2, during the voltage non-applied period, the liquidcrystal molecules are oriented perpendicularly to the surface of thealignment film 231. In the present embodiment, the protrusion 25 isformed in parallel to the source bus 12, as a result of which theprojected portion 241 is formed on the color filter substrate 200 incorrespondence with the protrusion 25. In this case, the liquid crystalmolecule 33 existing around a slope 241 a of the projected portion 241is oriented perpendicularly to the slope 241 a, with the result that theliquid crystal molecule 33 is oriented to slightly incline from thevertical direction with respect to the substrates 10 and 200. If avoltage is applied in this situation where the liquid crystal moleculesare oriented as above, electric force lines develop as indicated bybroken lines. During the voltage non-applied period, as shown in FIG. 2,the liquid crystal molecules existing in positions away from the slope241 a are oriented substantially perpendicularly to the substrates 10and 200, whereas the liquid crystal molecule 33 present around the slope241 a is slightly inclined. Therefore, immediately after the appearanceof the electric force lines, the electric force lines are inclined withrespect to the liquid crystal molecule 33 present around the slope 241 aas well as the liquid crystal molecules 31 and 32 present around theslit 13 b and the gap 14. As a result, when a voltage is applied betweenthe substrates 10 and 200, the liquid crystal molecule 33 existingaround the slope 241 a in addition to the liquid crystal molecules 31and 32 starts to be inclined horizontally to the substrates 10 and 200prior to most of the other liquid crystal molecules. That is, in thepresent embodiment, a large number of liquid crystal molecules existingbetween the substrates 10 and 200 start to be inclined horizontally tothe substrates 10 and 200 in a chained manner, from the liquid crystalmolecule 33 existing around the slope 241 a in addition to the liquidcrystal molecules 31 and 32, as their starting points. In this case,when considering the electric force lines entering/leaving the liquidcrystal molecules 31, 32 and 33, the liquid crystal molecules 31 and 32existing around the slit 13 b and the gap 14 are inclined in theclockwise direction T and the counterclockwise direction T′,respectively, and the liquid crystal molecule 33 existing around theslope 241 a is inclined in the clockwise direction T. That is, althoughthe liquid crystal molecule 32 near the gap 14 is inclined in thecounterclockwise direction T′, the liquid crystal molecule 31 existingaround the slit 13 b and the liquid crystal molecule 33 existing aroundthe slope 241 a are both inclined in the clockwise direction T.Accordingly, most of the liquid crystal molecules present in the regionsA and B are greatly influenced by the liquid crystal molecules 31 and 33inclined in the clockwise direction T among the liquid crystal molecules31, 32 and 33, and sequentially become inclined in the clockwisedirection T.

Consequently, most of the liquid crystal molecules present in theregions A and B are oriented in substantially the same direction asshown in FIG. 3. When comparing FIG. 3 with FIG. 9, a disclination isgenerated on the boundary between the regions A and B in FIG. 9, whereassuch disclination has disappeared and the light transmittance has beenimproved in FIG. 3. In this first embodiment, the light transmittance isincreased by about 12% in comparison with the prior art described withreference to FIGS. 6 to 9.

In the first embodiment, the protrusions 22, 25, 26 and 27 are formed ina mutually-connected continuous manner. Thus, the projected portions 241are also formed in a mutually-connected continuous manner over the wholesurface of the color filter substrate 200. However, it is also possibleto form the protrusions 22, 25, 26 and 27 physically separately from oneanother, to thereby form physically separated projected portions 241.

Further, in the first embodiment, the projection 25 parallel to thesource bus 12 is formed over the whole length of the source bus 12, sothat the projected portion 241 caused by the protrusion 25 is alsoformed over the whole length of the source bus 12. However, the lengthof the projected portion 241 may be shorter than that of the source bus12.

Moreover, in the first embodiment, the protrusions 25 parallel to thesource bus 12, the protrusion 26 parallel to the gate bus 11, and theprotrusion 27 opposing the central portion of the pixel electrode 13have been provided so as to form the projected portions 241 on the colorfilter substrate 20. However, it is not necessary to provide all thethree kinds of protrusions 25, 26 and 27, and provision of at least oneof the three kinds of protrusions results in formation of a projectedportion 241 which is different from the projected portions 24 (see FIG.7) caused by the protrusions 22 parallel to the slits 13 b, whereby animprovement in transmissivity of light may be obtained. Hereinafter,description will be made of another example, as a second embodiment ofthe liquid crystal display device according to the present invention,provided only with those protrusions 25 of the aforementioned threekinds of protrusions which are parallel to the source bus 12.

FIG. 4 is a plan view of the device wherein only the protrusions 25parallel to the source bus 12 are provided. In the following descriptionof the liquid crystal panel of FIG. 4, those components identical withthose of the liquid crystal panel shown in FIG. 1 are indicated by thesame reference numerals, respectively, and only those points differentfrom the liquid crystal panel shown in FIG. 1 will be described.

The difference between the liquid crystal panel of FIG. 4 and the liquidcrystal panel of FIG. 1 is that the liquid crystal panel shown in FIG. 4is provided only with the protrusions 25 of the protrusions 25, 26 and27 to form projected portions, whereas the liquid crystal panel shown inFIG. 1 is formed with the protrusion 25 parallel to the source buses 12,the protrusion 26 parallel to the gate bus 11, and protrusion 27opposing the central portion of the pixel electrode 13, in addition tothe protrusions 22 parallel to the slits 13 b, so as to form theprojected portions 241.

When the projected portions are formed in this way by combining theprotrusions 22 parallel to the slits 13 b and the protrusions 25parallel to the source buses 12, the transmissivity of light isincreased by about 10% in comparison with the conventional exampledescribed with reference to FIGS. 6 through 9.

In the first and second embodiments, the slits 13 a, 13 b and 13 c areprovided in each pixel electrode 13 of the TFT substrate 10. However,instead of providing the slits 13 a, 13 b and 13 c in each pixelelectrode 13, it is possible to form a flat pixel electrode 13 withoutslits 13 a, 13 b and 13 c and to provide protrusions between the flatlyformed pixel electrode 13 and the alignment film 15. When theprotrusions are provided between the pixel electrode 13 and alignmentfilm 15 in this way, the surface of the TFT substrate is formed withportions extending toward the liquid crystal layer 30. Thus, thoseliquid crystal molecules near these projected portions are inclined withrespect to electric force lines similarly to those liquid crystalmolecules near the projected portions 241 of the color filter substrate200, and act as starting points for aligning most of the liquid crystalmolecules. Consequently, most of the liquid crystal molecules arealigned in one direction during the voltage-applied period, therebycontributing to an improvement in the light transmissivity. It is alsopossible to provide protrusions between the pixel electrode 13 and thealignment film 15 and to further provide slits in the pixel electrode13, to thereby form a combination of the protrusions and the slits. Bysuch combination of the protrusions and the slits, there will alsoappear liquid crystal molecules inclined with respect to electric forcelines, which eventually contribute to the improvement of the lighttransmissivity. On the other hand it is possible to provide only slitsin both the pixel electrodes 13 and the common electrode 21, 212.

In the first and second embodiments described above, the lighttransmissivity has been improved by providing the color filter substrate200 with the protrusions 22, 25, 26 and 27. However, it is also possibleto improve the light transmissivity by providing the common electrode 21with slits, instead of providing the protrusions 22, 25, 26 and 27.Hereinafter, description will be made on another example in which thecommon electrode is provided with slits, as a third embodiment of thepresent invention.

FIG. 5 is a view schematically showing a cross section of a liquidcrystal display device having a common electrode provided with slits.

A color filter substrate 201 is provided with a layer 211 comprising ablack matrix and colored layers of RGB, and a common electrode 212having slits 212 a is formed on the layer 211. Further, the color filtersubstrate 201 is formed with an alignment film 232 so as to cover thecommon electrode 212 having the slits 212 a.

By providing the common electrode 212 with the slits 212 a in this way,the electric force lines near the slits 212 a are slightly bent, andenter or exit from the common electrode 212. Thus, similarly to theelectric force lines near the slits (see FIG. 2) provided in the pixelelectrode 13 of the TFT substrate, the electric force lines near theslits 212 a obliquely enter or exit from the liquid crystal molecules.That is to say, the liquid crystal molecules near the slits 212 a becomestarting points for aligning other liquid crystal molecules. As aresult, during the voltage-applied period, most of the liquid crystalmolecules are aligned in one direction, thereby eventually contributingto improving the light transmissivity.

Description has been made on examples where the color filter substrateis provided with protrusions with reference to the first and secondembodiments and on an example in which the common electrode on the colorfilter substrate is provided with slits with reference to the thirdembodiment. However, it is possible to provide the color filtersubstrate with protrusions and to further provide the common electrodewith slits, to thereby from combination of the protrusions with theslits.

In the above description, examples in which a combination of a TFTsubstrate and a color filter substrate is used as substrates sandwichinga liquid crystal layer therebetween have been taken. However, thecombination is not limited to that of a TFT substrate and a color filtersubstrate, and may be one in which an MIM (Metal Insulator Metal)substrate formed with MIM elements is combined with a color filtersubstrate.

Advantageous Effects of the Invention.

As described above, according to the liquid crystal display device ofthe present invention, the transmissivity of light through the liquidcrystal layer during the application of a voltage thereto can beimproved.

DESCRIPTION OF REFERENCE NUMERALS

10 TFT substrate 11 gate bus 12 source bus 13 pixel electrode 13a, 13b,13c, 212a slit 14 gap 15, 23, 231, 232 alignment layer 20, 200, 201color filter substrate 21, 212 common electrode 22, 25, 26, 27protrusion 24, 241 projected portion 30 liquid crystal layer 31, 32, 33liquid crystal molecule 241a slope

What is claimed is:
 1. A liquid crystal display device, comprising: afirst substrate having a pixel electrode and a first alignment film,wherein at least one of a first condition and a second condition must besatisfied, wherein the first condition is that the pixel electrode hasat least one first slit, and wherein the second condition is that thefirst substrate has at least one first protrusion between the pixelelectrode and the first alignment film; and a second substrate having acommon electrode and a second alignment film, wherein the firstsubstrate and the second substrate are sandwiching a liquid crystallayer therebetween, wherein the second substrate has at least one secondprotrusion between the common electrode and the second alignment film,wherein a protrusion of the at least one second protrusion extends in adirection different from the direction in which a slit of the at leastone first slit extends or from the direction in which a protrusion ofthe at least one first protrusion extends, wherein the at least onesecond protrusion includes a protrusion P that has an side edge portionand a remaining portion, and wherein an edge portion of the pixelelectrode overlaps with the side edge portion of the protrusion P anddoes not overlap with the remaining portion of the protrusion P.
 2. Theliquid crystal display device of claim 1, wherein the pixel electrodehas said at least one first slit, and wherein the first substrate doesnot have said at least one first protrusion.
 3. The liquid crystaldisplay device of claim 1, wherein the pixel electrode does not havesaid at least one first slit, and wherein the first substrate has saidat least one first protrusion.
 4. The liquid crystal display device ofclaim 1, wherein the pixel electrode has said at least one first slit,and wherein the first substrate has said at least one first protrusion.5. liquid crystal display device of claim 1, wherein the first substratehas a gate bus and a source bus, wherein the at least one secondprotrusion further includes a protrusion P₁ and a protrusion P₂, whereinthe protrusion P₁ is parallel to the source bus, and wherein theprotrusion P₂ is parallel to the gate bus.
 6. The liquid crystal displaydevice of claim 5, wherein the at least one second protrusion furtherincludes a protrusion P₃ that opposes a central portion of the pixelelectrode, and wherein the protrusion P₃ is perpendicular to the sourcebus.
 7. The liquid crystal display device of claim 6, wherein the commonelectrode has at least one second slit, and wherein the at least onesecond protrusion further includes a protrusion P₄ that is parallel to aslit of the at least one second slit.
 8. The liquid crystal displaydevice of claim 7, wherein the protrusions P₁, P₂, P₃, and P₄ areconnected in a mutually-connected continuous manner.
 9. The liquidcrystal display device of claim 7, wherein the protrusions P₁, P₂, P₃,and P₄ are not connected in a mutually-connected continuous manner andare physically separated from one another.
 10. The liquid crystaldisplay device of claim 5, wherein the protrusion P₁ projects onto thewhole length of the source bus.
 11. The liquid crystal display device ofclaim 5, wherein the protrusion P₁ projects onto less than the wholelength of the source bus.
 12. The liquid crystal display device of claim1, wherein the common electrode has at least one second slit, andwherein the at least one second protrusion further includes a protrusionP₄ that is parallel to a slit of the at least one second slit.
 13. Theliquid crystal display device of claim 1, wherein the common electrodehas at least one second slit, and wherein at least one second slitincludes a slit S₁ and a slit S₂, and wherein S₁ is parallel to S₂. 14.The liquid crystal display device of claim 1, wherein the commonelectrode has at least one second slit, and wherein at least one secondslit includes a slit S₁ and a slit S₂, and wherein S₁ is not parallel toS₂.